The present invention relates to a method and apparatus for calculating a PMV (Predicted Mean Vote) value corresponding to predicted mean thermal sensitivity representing the degree of comfort in an indoor environment or room. The present invention further relates to a method and apparatus for controlling the degree of comfort in an room through the use of an environment measuring unit that measures and supplies information about the environmental conditions present in the room to an environment control apparatus.
There have been tremendous improvements in the control of environmental conditions in the rooms or offices of a building. However, tenants are not satisfied with the mere cooling and heating provided by normal air-conditioning and heating units. The following needs have become increasingly apparent and are drawing a lot of attention:
The desire to maintain thermal comfort in the office environment; PA1 The desire to keep office air clean; PA1 The desire to remove unpleasant odor and fill the office with good smell; PA1 The desire to decrease noise and maintain quietness; and PA1 The desire to keep the lighting appropriate PA1 Thermal Comfort PA1 Indoor Air Quality PA1 Odor & Perfume PA1 Sound Noise PA1 Lighting PA1 Air Temperature (Ta) PA1 Radiant Temperature (Tr) PA1 Air Velocity (Vair) PA1 Humidity (RH) PA1 Human Activity (Met) PA1 Clothing (Icl) PA1 (Predicted Mean Vote) PA1 SET* (New Standard Effective Temperature) PA1 M=Metabolism (W/m) PA1 W=External Work, equal to zero from most metabolism PA1 Icl=Thermal Resistance of clothing (clo) PA1 fcl=The ratio of the surface of the closed body to the surface area of the nude body (N.D.) PA1 Ta=Air temperature (.degree.C.) PA1 Tr=the mean radiant temperature (.degree.C.) PA1 Vair=Relative air velocity (m/s) PA1 Despite the fact that the Fanger PMV equation has been adopted by ISO as ISO 7730, no one has been successful in developing a PMV sensor practically applicable to air-conditioning or heating. The Danish firm Bruel & Kjaer has developed, under the guidance of Prof. Fanger, a PMV measuring instrument for use in laboratory. However, because this instrument is designed specifically for laboratory use, the humidity, metabolism Met, and thermal resistance Icl of clothing are externally input; the sizes of the sensor and signal processing unit box are relatively large; and the instrument's range of operation with respect to the radiant temperature and air velocity is quite limited.
In order to meet with the above needs successfully, more parameters than temperature and humidity must be measured for control purposes. In addition, their inter-relationships must be studied to provide a more accurate means for gauging and controlling the comfort index of a particular room or environment.
The concept of environmental comfort is catching on with the general public in many areas, and it is a current topic at various seminars and other gatherings. The interest in environmental comfort is increasing rapidly in industry as well as in higher education, however, no competitive product has yet been seen in the area of air-conditioning or heating.
In the development of the only known comfort sensor applicable to heating and air-conditioning, we began with the study of the definition of comfort for an indoor environment. Indoor comfort is related to many things such as the following:
Thermal comfort is related to the coldness and warmness human beings feel psychologically and physiologically. The following 6 parameters have been defined as those factors which cause the sensation of coldness and warmness felt by humans.
There have been a few indices introduced as thermal comfort indices to evaluate these parameters, and the following two are particularly well known.
PMV is an index introduced by Professor Fanger of the Technical University of Denmark which indicates the sensations of cold and warmth felt by humans on a scale of +3 through -3 (+3 being very warm, 0-comfortable and -3--very cold). PMV is interrelated to the 6 parameters listed above and is an average value that represents how numerous people feel about cold and warmth, while individual differences are associated with the relationship between PMV and PPD (Predicted Percentage of Discomfort). This PVM index has been adopted by the International Standards Organization (ISO) as ISO 7730.
Prof. Fanger worked with over 1,300 people of both sexes, of various races and ages and from various parts of the world. The professor collected data from these individuals by having each undergo testing in an environmental laboratory with those 6 parameters varied. At the same time, he looked into the heat balance mechanism of the human body and ascertained that there were 7 ways for the body to lose heat energy after it had been generated from the foods the body took in: heat loss by motion; by water vaporization (through the skin to the environment, through the evaporation of sweat, through the water vapor in breath, through the temperature difference in breathing, through radiation); and by air flow.
As a result of such studies, Prof. Fanger formulated the following PMV equation and determined constants that were used in the equation from data collected through experiments involving the large number people. The Fanger PMV equation is designed for specific application to humans as shown below by association of the terms of the equation with their corresponding human energy parameters. ##EQU3## and where PMV=Predicted Mean Vote
In addition, the Fanger PMV equation itself does not suggest or imply anything which might lead to the development of an accurate sensor directly applicable to heating or air conditioning. This is because the Fanger PMV equation is of a recursive construction with respect to clothing thermal resistance term Tcl such that any effort to design a sensor based upon the parameters of the conventional PMV equation would not be accurate. Since the radiant heat change equation R=3.96 fcl [(Td+273).sup.4 -(Tr+273).sup.4 ] contains terms to the fourth power, the microcomputer used for calculating the PMV index is required to accurately calculate the value of R. In this respect, calculation of the PMV index is significantly prolonged because the microcomputer must repeatedly obtain values for the surface temperature of clothing due to the fact that the following parameter has to be repeatedly calculated. EQU Tcl-Tsk[3.06fcl{(Tcl+273).sup.4 -(Tr+273).sup.4 }+fcl hc (Tcl-Ta)].times.0.155Tcl.
Furthermore, the conventional PMV equation is a collection of a large number of terms, and has a very complicated formation, e.g., biquadractic terms of Tcl and Tr and repetitive calculations of Tcl. Hence, complicated arithmetic processing is required so that the processing time is further prolonged. Moreover, the cost of a PMV calculating apparatus arranged on the basis of the conventional PMV equation is inevitably increased, thus posing some practical difficulties in the use of such a PMV calculating apparatus as a PMV comfort sensor for building air-conditioning or heating.